KR101806345B1 - Pneumatic bearing with bonded polymer film wear surface and production method thereof - Google Patents

Abstract

An air bearing having a bonded polymer film coated surface and a method of making the same are disclosed. For example, an air bearing for supporting a payload is disclosed. The air bearing has a bearing surface with a polyimide membrane fastened to the substrate using a bonding layer. The polyimide membrane comprises a poly-oxydiphenylene-pyromelliticide and the bonding layer comprises diglycidyl ether of bisphenol A, 1,4-butanediol diglycidyl ether, and 2,2,4- Trimethylhexamethylene-1,6-diamine.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an air bearing having an adhesive polymer coated surface and a method of manufacturing the air bearing.

Dissemination of related applications

This application claims priority of U.S. Provisional Application No. 61 / 357,771, filed June 23, 2010, which is incorporated herein by reference.

The present invention relates generally to lithography, and more particularly to pneumatic bearings.

Lithography is widely recognized as a key process in the manufacture of integrated circuits (ICs) and other devices and / or structures. A lithographic apparatus is used during lithography and is a machine that applies a pattern onto a substrate, typically onto a target portion of the substrate. During fabrication of an IC using a lithographic apparatus, a patterning device (alternatively, also referred to as a mask or a reticle) produces a circuit pattern to be formed in an individual layer of the IC. This pattern may be transferred onto a target portion (e.g. comprising a portion of a die, a die or several dies) on a substrate (e.g. a silicon wafer). Transfer of the pattern is typically performed through imaging onto a layer of radiation-sensitive material (resist) provided on the substrate. In general, a single substrate will comprise a network of adjacent target portions that are successively patterned. The manufacture of different layers of IC often requires imaging of different patterns on different layers with different reticles. Thus, reticles and substrates must be changed during the lithography process. In order to facilitate reticle handling, air bearings are provided on the stages supporting the reticles.

Bearings are devices that reduce friction between moving parts and / or support moving loads. There are two main types of bearings. Anti-friction bearings minimize friction by using devices such as roller bearings or ball bearings. Friction bearings minimize friction by using active lubrication or other means to facilitate movement between moving parts. Friction bearings are also known as sliding bearings. Many bearing assemblies, for example lubricated ball bearing assemblies, take advantage of both principles.

Air bearings are examples of friction or sliding bearings. This uses compressed air to create a consistent gas film on which the bearing surface lies and moves. The gas film acts as a virtually frictionless lubricant to promote smooth movement between the air bearing surfaces. The bearing surface from which the lubricating gas film is produced is referred to as the "active surface ". Typically, air bearings require at least a steady source of compressed air to hold the lubricating gas film.

As noted above, there is an example of a semiconductor lithography environment as an example environment for air bearings. There, air bearings offer many advantages. The air bearings are virtually frictionless and therefore do not produce abrasive materials of the particles as they operate. These particulate materials are problematic in ultra-clean semiconductor manufacturing environments. Additionally, the lubricant present in the ball or roller bearing may be outgas contaminant molecules, which is also detrimental to the semiconductor manufacturing environment. Also, air bearings require relatively little maintenance or regular repairs.

Despite all of these advantages, "dry" contact between air bearing surfaces can scratch conventional air bearing surfaces in use and degrade their performance. To solve this problem, conventional bearings are placed on the guideway of polished granite or chrome-plated steel while the bearings themselves are made of case-hardened stainless steel -ardened stainless steel. The case-hardening process provides abrasion resistance, corrosion resistance, and resistance to galling by curing the surface layer of the steel. The bulk of the steel remains unhardened, so the hardening is maximum at the surface and is rapidly and continuously reduced as a direct function of the distance from the surface. Unfortunately, the case-hardening process requires a slight modification of the bearing to allow the bearing to rebond, which partially and somewhat unevenly removes the cured layer. The final product is a functional flat bearing, but the thickness of the cured surface layer is not uniform across the bearing surface and varies between bearings depending on the polishing depth required to regain flatness. In common sense, the hardness of the bearing can not be tightly controlled by the case-hardening process.

The non-uniformity of the cured surface layer is exacerbated in the case of different seal bearings used in lithographic reticle handler modules made of steel plates that are larger and an order of magnitude larger than the stage bearings. Thin steel sheets tend to be permanently deformed by any treatment necessary for heating the parts including the case-hardening process. In a vacuum environment, case-hardened steel provides good wear resistance, does not generate excessive amounts of particles, and is relatively inexpensive. Therefore, case-hardened steel has typically been selected for surface treatment.

There is a continuing need for improvements in air bearing design. This applies particularly to semiconductor lithography tool technology, where more precise tolerances and faster speeds are continuously required for manufacturing tools.

As described above, there is a need for a method of forming an air bearing surface that is vacuum-compatible and can operate without lubricant even in the absence of a gas input in a bearing that includes dry sliding. In addition, air bearing surfaces are required that generate only very small particles, even if they generate particles under these conditions to avoid contamination of the vacuum chamber. Improved air bearings should also be inexpensive. To meet these needs, embodiments of the present invention are directed to an air bearing having a bonded polymer film covering surface and a method of making the same.

For example, one embodiment of the present invention provides an air bearing having a bearing surface comprising a substrate, a bonding layer disposed on the substrate, and a polyimide film disposed on the bonding layer. The substrate may be a ceramic material, and the bonding layer may be selected from the group consisting of diglycidyl ether of bisphenol A, 1,4-butanediol diglycidyl ether, And 2,2,4-trimethylhexamethylen-1,6-diamine. The polyimide film comprises poly-oxydiphenylene-pyromellitimide and can be in the range of about 7 to 100 microns, preferably at least 25 microns in thickness. Air bearings can be used in lithographic apparatus.

In a further example, an embodiment of the present invention provides a method of manufacturing a bearing surface of an air bearing. The method may include disposing a polyimide film on a flat surface of a vacuum chuck, applying a vacuum to the polyimide film, and disposing a liquid epoxy on a surface of the polyimide film. The substrate can be placed on the liquid epoxy without contacting the substrate with the polyimide film. The substrate is released onto the liquid epoxy, and a weight is placed on the substrate. The liquid epoxy is cured and the weight is removed. The polyimide film is released from the vacuum chuck. The polyimide film may be trimmed to match the contour of the substrate.

Additional features and advantages of the present invention, as well as the structure and operation of various embodiments of the present invention, will be described in more detail below with reference to the accompanying drawings. It should be noted that the present invention is not limited to the specific embodiments described herein. These embodiments are merely exemplary in the present disclosure. Based on the teachings contained herein, one of ordinary skill in the art will understand additional embodiments.

The accompanying drawings, which are incorporated in and form a part of this specification, illustrate the present invention. Further, the drawings, together with the description, serve to explain the principles of the invention and to enable those skilled in the art to make and use the invention.
Figures 1A and 1B show a reflective and transmissive lithographic apparatus, respectively,
Figure 2 shows an exemplary EUV lithographic apparatus,
Figure 3 shows an exemplary air bearing with a bonded polymer membrane covering surface according to the present invention,
Figure 4 is a flow chart of an exemplary method of manufacturing an air bearing with a bonded polymer membrane coated surface according to the present invention,
Figures 5a-5g illustrate an exemplary method of making an air bearing with a bonded polymer membrane coated surface according to the present invention,
Figure 6 is a flow chart of another exemplary method of manufacturing an air bearing with a bonded polymer membrane coated surface according to the present invention.
The drawings in this specification are not drawn to scale. The features and advantages of the present invention will become more apparent from the following detailed description, when taken in conjunction with the drawings, in which like reference numerals refer to like elements throughout. In the drawings, like reference numbers generally indicate the same, functionally similar, and / or structurally similar elements. The drawing in which an element first appears is represented by the leftmost digit (s) of the corresponding reference character.

Ⅰ. survey

The present invention relates to a bonded polymer film coated surface and a method of manufacturing the same. This specification discloses one or more embodiments that include the features of the present invention. The disclosed embodiments (s) are merely illustrative of the present invention. The scope of the present invention is not limited to the disclosed embodiment (s). The invention is defined by the following claims.

This description is provided in the context of semiconductor lithography techniques. This environment has been chosen to best illustrate certain features of the present invention. However, such an environment should not be construed as limiting the invention beyond the features set forth in the following claims. Of course, those skilled in the art will be able to envision various uses for air bearings having the features described herein, deviating from the semiconductor lithography tool background.

Reference in the specification to " the embodiment (s) " and "an embodiment "," the embodiment ", "the example embodiment ", etc., All embodiments do not necessarily include the specific features, structures, or characteristics. Also, these phrases are not necessarily referring to the same embodiment. Further, when a specific feature, structure, or characteristic is described in connection with an embodiment, it is to be understood that it is capable of carrying out such a feature, structure, or characteristic in connection with other embodiments within the knowledge of one of ordinary skill in the art do.

Air bearing with bonded polymeric coating surfaces and methods of making the same are disclosed. For example, an air bearing supporting a payload is disclosed. The air bearing has a bearing surface with a polyimide membrane fastened to the substrate as a bonding layer. In one embodiment, the polyimide membrane comprises an oxydiphenylene-pyromelliticide, wherein the bonding layer comprises diglycidyl ether of bisphenol A, 1,4-butanediol diglycidyl ether, and 2,2 , 4-trimethylhexamethylene-1,6-diamine. The bearing surface is vacuum compatible and can operate without lubricant if the gas input is not present in bearings that include dry sliding. In addition, the bearing surface generates only very small particles under dry sliding conditions to avoid contamination of the chamber. This solution is also low-cost when compared to conventional air bearings.

Embodiments of the present invention enable the replication of useful high-level tooling surfaces using inexpensive materials and simple processes. High performance, robustness and durability are achieved, while the expensive precision polishing and heat treatment steps are omitted. As an additional advantage, metal-to-metal wear in a vacuum environment is eliminated.

However, before describing these and other embodiments, it is intended to suggest an exemplary environment in which embodiments of the invention may be implemented.

Ⅱ. Illustrative Lithography  Environment

A. Exemplary Reflective and Transmissive Lithography  system

Figures 1A and 1B schematically depict a lithographic apparatus 100 and a lithographic apparatus 100 '. Each of the lithographic apparatus 100 and the lithographic apparatus 100'includes an illumination system (illuminator) IL configured to condition a radiation beam B (e.g., DUV radiation or EUV radiation); A support structure (not shown), configured to support a patterning device (e.g., a mask, reticle, or dynamic patterning device) MA and coupled to a first positioner PM configured to accurately position the patterning device MA For example, a mask table) MT; And a substrate table (e.g., a wafer table) PW configured to hold a substrate (e.g., a resist-coated wafer) W and connected to a second positioner PW configured to accurately position the substrate W Table) WT. The lithographic apparatus 100 and 100'may also be provided with a patterning device MA for imparting a radiation beam B onto a target portion C (e.g. comprising one or more dies) (PS) configured to project the patterned pattern. In the lithographic apparatus 100, the patterning device MA and the projection system PS are reflective and the patterning device MA and the projection system PS in the lithographic apparatus 100 'are transmissive.

The illumination system IL may include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic or other types of optical components, or any combination thereof, for directing, shaping, May include components.

The support structure MT may depend on the orientation of the patterning device MA, the design of the lithographic apparatus 100 and 100 ', and other conditions such as, for example, whether the patterning device MA is maintained in a vacuum environment And holds the patterning device MA in a manner as described above. The support structure MT may utilize mechanical, vacuum, electrostatic, or other clamping techniques to hold the patterning device MA. The support structure MT may be, for example, a frame or a table, which may be fixed or movable as required. The support structure MT may ensure that the patterning device is at a desired position, for example with respect to the projection system PS.

The term "patterning device" (MA) refers to any device that can be used to impart a pattern to a cross-section of a radiation beam B, in order to create a pattern in a target portion C of the substrate W Should be interpreted broadly. The pattern imparted to the radiation beam B may correspond to a particular functional layer in the device to be created in the target portion C, such as an integrated circuit.

The patterning device MA may be transmissive (as in lithographic apparatus 100 'of FIG. 1B) or reflective (as in lithographic apparatus 100 of FIG. 1A). Examples of the patterning device MA include reticles, masks, programmable mirror arrays, and programmable LCD panels. Masks are well known in the lithographic arts and include various types of hybrid masks as well as mask types such as binary, alternating phase-shift and attenuated phase-shift types. One example of a programmable mirror array employs a matrix configuration of small mirrors, each of which can be individually tilted to reflect an incoming radiation beam in different directions. The tilted mirrors impart a pattern to the radiation beam B reflected by the mirror matrix.

The term "projection system" (PS) is intended to encompass all types of optical components, including refractive, reflective, catadioptric, magnetic, electromagnetic and electrostatic Optical system, or any combination thereof, for directing, shaping, or controlling radiation. Other gases can absorb too much radiation or electrons, so a vacuum environment can be used for EUV or electron beam radiation. Thus, a vacuum environment can be provided in the entire beam path with the aid of vacuum walls and vacuum pumps.

The lithographic apparatus 100 and / or the lithographic apparatus 100 'may be of a type having two (dual stage) or more substrate tables (and / or two or more mask tables). In such "multiple stage" machines, preparatory steps may be performed on one or more other tables while an additional substrate table WT is used in combination, or while one or more substrate tables WT are being used for exposure. In lithographic apparatus 100, one or more movable parts of the apparatus may be provided with air (e.g., air) bearings. For example, devices such as the substrate table WT, the mask table MT, and the reticle handling device may be supported by air bearings.

Referring to Figs. 1A and 1B, the illuminator IL receives a radiation beam from a radiation source SO. For example, when the source SO is an excimer laser, the source SO and the lithographic apparatus 100, 100 'may be separate entities. In this case, the source SO is not considered to form part of the lithographic apparatus 100, 100 ', and the radiation beam B may, for example, comprise a suitable directing mirror and / or a beam expander Is transmitted from the source SO to the illuminator IL with the aid of the included beam delivery system BD (Fig. 1B). In other cases, for example, where the source SO is a mercury lamp, the source SO may be an integral part of the lithographic apparatus 100, 100 '. The source SO and the illuminator IL may be referred to as a radiation system together with a beam delivery system BD if necessary.

The illuminator IL may comprise an adjuster AD (FIG. 1B) for adjusting the angular intensity distribution of the radiation beam. Generally, at least the outer and / or inner radial extent (commonly referred to as -outer and -inner, respectively) of the intensity distribution in the pupil plane of the illuminator can be adjusted. In addition, the illuminator IL may include various other components (Figure 1B), such as an integrator IN and a condenser CO. The illuminator IL may be used to condition the radiation beam so that the cross section of the radiation beam has a desired uniformity and intensity distribution.

1A, a radiation beam B is incident on a patterning device (e.g., mask) MA, which is held in a support structure (e.g., a mask table) MT, As shown in FIG. In the lithographic apparatus 100, the radiation beam B is reflected from the patterning device (e.g. mask) MA. After being reflected from the patterning device (e.g. mask) MA, the radiation beam B passes through the projection system PS, which projects the radiation beam B onto a target portion C). With the aid of the second positioner PW and the position sensor IF2 (e.g. interferometric device, linear encoder or capacitive sensor), the substrate table WT is moved, for example, Can be moved accurately to position different target portions C in the path. Similarly, a first positioner PM and another position sensor IF1 may be used to accurately position the patterning device (e.g. mask) MA with respect to the path of the radiation beam B . The patterning device (e.g. mask) MA and the substrate W may be aligned using mask alignment marks M1, M2 and substrate alignment marks Pl, P2.

1B, a radiation beam B is incident on a patterning device (e.g., mask MA) held in a support structure (e.g., mask table MT) and is patterned by a patterning device . After traversing the mask MA, the radiation beam B passes through the projection system PS and the projection system focuses the beam onto a target portion C of the substrate W. With the aid of the second positioner PW and the position sensor IF (e.g. interferometric device, linear encoder or capacitive sensor), the substrate table WT can be moved, for example, Can be moved accurately to position different target portions C in the path. Similarly, the first positioner PM and other position sensors (not explicitly shown in FIG. 1B) may be used to detect the position of the beam of radiation (e.g., a beam of radiation) after mechanical retrieval from, for example, B of the mask MA.

In general, the movement of the mask table MT may be realized with the aid of a long-stroke module and a short-stroke module, 1 positioner PM. Similarly, movement of the substrate table WT may be realized using a long-stroke module and a short-stroke module, which form a part of the second positioner PW. In the case of a stepper (as opposed to a scanner), the mask table MT may only be connected or fixed to the short-stroke actuators. The mask MA and the substrate W may be aligned using the mask alignment marks M1 and M2 and the substrate alignment marks P1 and P2. Although the illustrated substrate alignment marks occupy dedicated target portions, they may be located in spaces between target portions (these are known as scribe-lane alignment marks). Similarly, in situations where more than one die is provided on the mask MA, the mask alignment marks may be located between the dies.

The lithographic apparatus 100 and 100 'may be used in at least one of the following modes:

1. In step mode, the support structure (e.g., mask table) MT and the substrate table WT are kept essentially stationary while the entire pattern imparted to the radiation beam B is transferred to the target portion C) (i.e., a single static exposure). The substrate table WT is then shifted in the X and / or Y direction so that a different target portion C can be exposed.

2. In scan mode, the support structure (e.g., mask table) MT and the substrate table WT are scanned synchronously while the pattern imparted to the radiation beam B is projected onto the target portion C (I.e., a single dynamic exposure). The speed and direction of the substrate table WT relative to the support structure (e.g., mask table) MT may be determined by the magnification (image reduction) and image reversal characteristics of the projection system PS.

3. In another mode, the support structure (e.g., mask table) MT is kept essentially stationary holding a programmable patterning device so that a pattern imparted to the radiation beam B is projected onto a target portion C, the substrate table WT is moved or scanned while being projected. A pulsed radiation source SO may be employed and the programmable patterning device is updated as needed after each movement of the substrate table WT or between successive radiation pulses during a scan. This mode of operation can be readily applied to maskless lithography using a programmable patterning device, such as a programmable mirror array of a type as referred to herein.

Combinations and / or variations on the above described modes of use, or entirely different modes of use, may also be employed.

Although specific reference may be made in this text to the use of lithographic apparatus in the manufacture of ICs, the lithographic apparatus described herein may have other applications, such as the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat-panel displays, It should be understood that other applications, such as the manufacture of displays (LCDs), thin film magnetic heads, may also be employed. It will be understood by those skilled in the art that any use of the terms "wafer" or "die" herein may be considered as synonymous with the more general terms "substrate" or "target portion", respectively, shall. The substrate referred to herein may be processed before or after exposure, for example in a track (typically a tool that applies a layer of resist to the substrate and develops the exposed resist), a metrology tool, and / or an inspection tool. Where applicable, the description herein may be applied to such substrate processing tools and other substrate processing tools. Further, the substrate may be processed more than once, for example in order to create a multi-layer IC, so that the term substrate used herein may also refer to a substrate that already contains multiple processed layers.

In a further embodiment, the lithographic apparatus 100 includes an extreme ultraviolet (EUV) source configured to generate a beam of EUV radiation for EUV lithography. Generally, an EUV source is configured within the radiation system (see below), and the corresponding illumination system is configured to condition the EUV radiation beam of the EUV source.

B. Illustrative EUV Lithography  Device

Figure 2 schematically depicts an exemplary EUV lithography apparatus 200 according to one embodiment of the present invention. In Figure 2, the lithographic apparatus 200 includes a radiation system 42, an illumination optical unit 44, and a projection system PS. The radiation system 42 includes a radiation source SO in which the radiation beam can be formed by a discharge plasma. In one embodiment, the EUV radiation is irradiated by a gas or vapor, such as xenon (Xe) gas, tin (Sn) vapor or lithium (Li) vapor, in which an ultra-high temperature plasma is generated to emit radiation within the EUV range of the electromagnetic spectrum Lt; / RTI > The ultrahigh temperature plasma may be generated, for example, by generating a plasma that is at least partially ionized by an electrical discharge. Efficient production of radiation may require, for example, Xe, Li, Sn vapor or other suitable gas or vapor with a partial pressure of 10 Pa. The radiation emitted by the radiation source SO is delivered from the source chamber 49 into the collector chamber 48 through a gas barrier or contaminant trap 49 located in or behind the opening in the source chamber 47. In one embodiment, the gas barrier 49 may comprise a channel structure.

The collector chamber 48 includes a radiation collector 50 (also referred to as a collector mirror or collector) that may be formed from a grazing incidence collector. The radiation collector 50 has an upstream radiation collector side 50a and a downstream radiation collector side 50b and the radiation passing through the collector CO is reflected by the lattice spectrum filter 51 to form a virtual Lt; RTI ID = 0.0 > 52 < / RTI > Radiation collectors 50 are known to those skilled in the art.

From the collector chamber 48 the radiation beam 56 is reflected by the illumination optical unit 44 through the normal incidence reflectors 53 and 54 and is reflected by a reticle or mask (not shown) located on the reticle or mask table MT ). A patterned beam 57 is formed which is imaged onto a substrate (not shown) that is supported on the wafer stage or substrate table WT via reflective elements 58 and 59 in the projection system PS. In various embodiments, the illumination optical unit 44 and the projection system PS may include more (or fewer) elements than those shown in FIG. For example, a grating spectral filter 51 may optionally be present depending on the type of lithographic apparatus. Further, in one embodiment, illumination optics unit 44 and projection system PS may include more mirrors than shown in Fig. For example, the projection system PS may include one to four reflective elements in addition to reflective elements 58 and 59. [ In FIG. 2, reference numeral 180 denotes a space between two reflectors, for example, a space between the reflectors 142 and 143.

In one embodiment, the collector mirror 50 may also include a normal incidence collector in addition to or in place of the grazing incidence mirrors. Also, the collector mirror 50 has been described with reference to a nested collector having reflectors 142, 143, and 146, but may also be used as an example of a collector.

Further, instead of the grating 51 shown in Fig. 2, a transmission optical filter may be applied. Optical filters that are transmissive to EUV, as well as optical filters that are less transmissive to, or even substantially absorb, UV radiation are known to those skilled in the art. Thus, the use of the term "lattice spectral purity filter" herein is interchangeably expressed as a "spectral purity filter" comprising lattice or transmissive filters. Although not shown in FIG. 2, the EUV transmission optical filter may be included as additional optical elements, for example, upstream of the optical EUV transmission filters or collector mirror 50 in the illumination unit 44 and / or the projection system PS As shown in FIG.

The terms "upstream" and "downstream" for optical elements represent the positions of one or more optical elements in the "optical upstream" and "optical downstream" of each of the one or more additional optical elements. The first optical elements, which are closer to the source (SO) than the second optical element, are arranged upstream of the second optical element along the optical path through which the radiation beam passes through the lithographic apparatus 200, 1 < / RTI > For example, the collector mirror 50 is configured upstream of the spectral filter 51, while the optical element 53 is configured downstream of the spectral filter 51.

All of the optical elements shown in FIG. 2 (and additional optical elements not shown in the schematic view of this embodiment) may be susceptible to the deposition of contaminants, such as Sn, generated by the source SO. This may be the case for the radiation collector 50 and, if present, the spectral purity filter 51. Thus, a cleaning device can be employed to clean one or more of these optical elements, as well as cleaning methods can be applied to the optical elements, and also the normal incidence reflectors 53 and 54 can be used as reflective elements 58 and < RTI ID = 59), or other optical elements, such as additional mirrors, gratings, and the like.

The radiation collector 50 may be a grazing incidence collector, and in this embodiment the collector 50 is aligned along the optical axis O. Also, the source SO, or an image thereof, may be disposed along the optical axis O. The radiation collector 50 may include reflectors 142, 143, and 146 (also known as a "shell" or a bolter-type reflector that includes several bolt-type reflectors). Reflectors 142, 143, and 146 can be nested and are rotationally symmetric about optical axis O. [ In Figure 2, the inner reflector is labeled 142, the middle reflector is labeled 143, and the outer reflector is labeled 146. The radiation collector 50 encompasses a volume, i.e., a volume within the outer reflector (s) Typically, the volume in the outer reflector (s) 146 is closed in the circumferential direction although small openings may be present.

Reflectors 142, 143, and 146 may each include a surface, at least a portion of which represents a reflective layer or a plurality of reflective layers. Thus, the reflectors 142, 143, and 146 (or additional reflectors in embodiments of the radiation collectors having three or more reflectors or shells) at least partially reflect and collect EUV radiation from the source SO, And at least some of the reflectors 142, 143, and 146 may not be designed to reflect and collect EUV radiation. At least a portion of the back side of the reflectors may not be designed to reflect and collect EUV radiation. The surfaces of these reflective layers may additionally have a cap layer as an optical filter or protective for at least part of the surface of the reflective layers.

The radiation collector 50 may be disposed in the vicinity of the image of the source SO or the source SO. Each of the reflectors 142, 143, and 146 may include at least two adjacent reflective surfaces and the reflective surfaces that are further from the source SO are more reflective than the reflective surface positioned closer to the source SO, (O). ≪ / RTI > In this manner, the grazing incidence collector 50 is configured to generate a (E) UV radiation beam propagating along the optical axis O. [ At least two reflectors may be arranged substantially coaxially and extend substantially rotationally symmetrical with respect to the optical axis (O). It should be appreciated that the radiation collector 50 may have additional features on the outer surface of the outer reflector 146, or additional features around the outer reflector 146, such as a protective holder, a heater, and the like.

In the embodiments described herein, the terms "lens" and "lens element" are intended to encompass all types of optical components, including refractive, reflective, magnetic, electromagnetic and electrostatic optical components, Any one or a combination thereof.

Also, the terms "radiation" and "beam ", as used herein, include particle beams, such as ion beams or electron beams, as well as particle beams (e.g., having a wavelength of 365, 248, 193, 157 or 126 nm) (EUV or soft X-ray) radiation (e.g. having a wavelength in the range of 5-20 nm, e.g. 13.5 nm), or a hard X-ray acting at a wavelength of less than 5 nm, It encompasses all forms of electromagnetic radiation, including. Generally, radiation having a wavelength of approximately 780 to 3000 nm (or more) is considered to be IR radiation. UV refers to radiation having wavelengths of approximately 100 to 400 nm. Within lithography, this is typically at wavelengths that can be generated by mercury discharge lamps: G-line 436 nm; H-line 405 nm; And / or I-line 365 nm. Vacuum UV, or VUV (i.e., UV absorbed by air) refers to radiation having radiation having a wavelength of approximately 100 to 200 nm. Generally, DUV (deep UV) refers to radiation having wavelengths in the range of 126 nm to 428 nm, and in one embodiment an excimer laser can generate DUV radiation used in the lithographic apparatus. For example, it should be understood that radiation having a wavelength in the range of 5-20 nm is associated with radiation having a specific radiation band at least in part in the range of 5-20 nm.

Ⅲ. Improved air bearing

A. Bonding Polymer  Having a film-coated surface flat  Air bearing

Figure 3 shows an exemplary air bearing 300 with a bonded polymeric membrane coated surface according to the present invention. As part of the air bearing 300, the polyimide film 302 is permanently bonded to the substrate 304 by a bonding agent 306. The air air bearing 300 may be used in lithography tools such as the lithographic apparatus 100, 100 'described above. For example, the substrate 304 may support the payload as part of a reticle handling apparatus that is part of the lithographic apparatus 100, 100 'described above.

The polyimide film 302 is a strong and durable polymer film. The preferred polyimide film 302 is manufactured in a film format by DuPont and is Kapton ^? Is a poly-oxydiphenylene-pyromellitic acid sold under the tradename < RTI ID = 0.0 > In one example, the polyimide film 302 is in the range of about 7 to 100 microns, with at least 25 microns being preferred.

The preferred bonding agent 306 is low viscosity and is a 2-part room temperature-curing epoxy such as Epo-tek ^? 2,2,4-trimethylhexamethylene-1,6-diamine sold under the trade name 301-2 epoxy, diglycidyl ether of bisphenol A, and 1,4-butanediol diglycidyl ether.

The substrate 304 has a non-cured surface, so that a strong, durable polymer film is bonded to the non-cured substrate to form the bearing surface. Thus, the opposite bearing surface can be left in its natural, low-strain non-curing condition. The substrate 304 can be a metal, for example stainless steel, and the opposite surface can be a material similar or not similar thereto, for example stainless steel. In addition, as will be appreciated by those skilled in the art, the selection material for the substrate 304 includes other materials, such as glass and ceramics, that are capable of achieving a high level of flatness. In a non-limiting example, the substrate 304 has a thickness of approximately 10 millimeters and a diameter of approximately 300 millimeters, and is approximately 3 to approximately 6 microns peak- to-valley surface flatness.

B. Bonding Polymer  Having a film-coated surface flat  Methods of manufacturing air bearings

4 is a flow chart of an exemplary method 400 of manufacturing an air bearing, e. G., An air bearing 300, with a bonded polymer film coated surface. 5A-5G also illustrate the different situations of the exemplary manufacturing method illustrated in FIG. In particular, Figures 5a-5g show in cross-section the manufacture of an exemplary annular air bearing with a bonded polymer film covering surface. The described method 400 may be used to produce an air bearing 300 having a bonded polyimide film 302 covering surface in a square, rectangular, annular, or other useful shape. According to this method 400, the surface flatness of the polyimide film 302 is better than the flatness of the substrate 304 and can be made sufficiently flat to be useful as an air bearing. This enables the production of a flat and flat membrane surface at relatively low cost because the substrate 304 requires less precise machining. As a further advantage, post-machining of the surface of the polyimide film 302 post-bonding is not required to achieve useful flatness. The method 400 may be performed in a clean room to reduce the possibility of contaminating the surface of the substrate 306 with debris.

In step 402, a vacuum chuck 502 is provided having a very flat, well-polished surface, as shown in FIG. 5A. The flatness of the flat surface of the vacuum chuck 502 determines the surface flatness of the polyimide film 302 at the finishing of the manufacturing process. The higher the flatness, the less likely the occurrence of dry sliding and the greater the uniformity of the gas pressure between the bearing surfaces and the guideways during bearing operation. The vacuum chuck 502 may have a flatness over the entire useful surface of approximately 2 microns peak-to-valley.

The flat surface of the vacuum chuck 502 is positioned perpendicular to gravity (e.g., level) so that the substrate 304 does not slide against the polyimide film 302 in steps 408-414. The polyimide film 302 is then placed on the flat surface of the vacuum chuck 502.

In step 404 shown in FIG. 5B, a vacuum is applied to the polyimide film 302 through a vacuum port 504, which may be, for example, a circular groove. This allows the polyimide film 302 to substantially conform to the flat surface of the vacuum chuck 502. This technique provides a useful, flat bearing surface to the finished bearing that does not require surface finishing of the polyimide membrane 302.

In step 406 shown in FIG. 5C, the premixed, de-vaporized liquid epoxy 306 is poured onto the polyimide film 302 in the form of, for example, a single continuous curve, Lt; / RTI > The applied epoxy 306 may have a thickness of 4 to 5 mm. For the annular substrate, the curve is closed. For a rectangular substrate, the epoxy 306 may be applied in the form of dots. The shape of the epoxy 306 applied to avoid air trapping between the substrate 304 and the polyimide film 302 in subsequent steps is selected according to the shape of the substrate 304. [ Figs. 5d-5g illustrate a ring-shaped substrate 304 as an example of the shape of the substrate 304. Fig. After application of the epoxy 306 to the polyimide film 302, the assembly may remain stationary for a period of time such that gravity distributes the epoxy 306 on the polyimide film 302 flatly. During this time, the gases trapped within the epoxy can also be vented.

In step 408 shown in FIG. 5D, the substrate 304 is disposed (e.g., lowered) on the epoxy 306. In one example, the substrate 304 is always kept horizontal (by external means) to gravity over slow downward motion. This prevents the epoxy 306 from being unevenly distributed between the substrate 304 and the polyimide film 302. As will be appreciated by those skilled in the art, other schemes for placing the substrate 304 on the epoxy 306, rather than using gravity, can be employed.

In step 410, the substrate is released in a controlled manner and is positioned on both the polyimide film 302 and the epoxy 306. In one example, the substrate 304 is released when the distance between the polyimide film 302 and the substrate 304 is approximately 0 to 1 mm, preferably approximately 0.5 mm, from the surface of the epoxy 306.

A weight 506 is disposed at the top of the substrate 304 to apply force (e.g., gravity) to the substrate 304 to squeeze the excess epoxy 306 (e. G., Gravity) For example, the place can be). In step 414, the epoxy 306 is cured according to the epoxy manufacturer's decision.

In step 416 shown in Figure 5f, the weight 506 is removed. At step 418, the partially completed bearing 508 is released from the vacuum chuck 502. Optionally, a compressed gas may be injected through the vacuum port 504 to facilitate removal.

In step 420 shown in FIG. 5G, the edge of the polyimide film 302 is trimmed to match the contour of the substrate 304. Trimming can be accomplished by a number of techniques that will be understood by those skilled in the art. The polyimide film 302 does not require surface polishing to improve its surface flatness and heat treatment to increase its hardness.

6 is a flow chart of an exemplary method 600 of manufacturing an air bearing, e. G., Air bearing 300, with a bonded polymer film covering surface. The described method 600 can be used to produce an air bearing 300 having a bonded polyimide film 302 covering surface in a square, rectangular, annular, or other useful shape. According to this method 600, the surface flatness of the polyimide film 302 is better than the flatness of the substrate 304 and can be made sufficiently flat to be useful as an air bearing. This allows the production of a useful and flat film surface at a relatively low cost since the substrate 304 requires less precise machining. As an additional advantage, post-machining of the surface of the polyimide film 302 post-bonding is not required to obtain useful flatness. The method 600 may be performed in a temperature-controlled clean room to reduce the possibility of contamination of the surface of the substrate 304 with debris.

In step 602, the substrate 304 is coated with a liquid epoxy 306. The coating may provide a substantially uniform layer of epoxy 306 at least 100 microns thick.

At step 604, the epoxy 306 is vented to allow gravity to cause the epoxy 306 to be distributed evenly on the substrate 304 and release the trapped gas from the epoxy 306. As a non-limiting example, it takes about 10 minutes to air out.

In step 606, the polyimide film 302 is unrolled from the epoxy 306. The surface tension of the epoxy 306 slowly pulls the polyimide film 302 onto the substrate 304. No external force need be applied to contact the polyimide film 302 and the epoxy 306.

In step 608, the polyimide film 302 is inspected for trapped gas pockets and particles between the polyimide film 302 and the substrate 304. The trapped gases are directed toward a portion of the epoxy 306 exposed to the atmosphere through the epoxy 306 and are subsequently discharged from the epoxy 306.

In step 610, the substrate / membrane assembly is inverted. If the substrate 304 has an annular shape, a vent is cut at the center of the polyimide film 302. Subsequently, the vent is used to transfer the gas across the polyimide membrane 302 during the manufacturing process.

In step 612, the substrate / membrane assembly is placed on an optically flat surface, such as a vacuum chuck 502. During placement, tilting of the substrate / membrane assembly is minimized. After placement, the polyimide film 302 is contacted with an optically flat surface.

At step 614, a force is applied to the substrate 304 to squeeze the excess epoxy 306. A weight may be applied to the substrate 304 to provide the force. The vent formed in step 610 releases trapped gas between the polyimide membrane 302 and the optically flat surface. The polyimide film 302 and the substrate 304 may be coated with an optically planar surface and a patterned surface to prevent the polyimide film 302 and the substrate 304 from sliding relative to each other on the epoxy 306, It can be confined to co-existence.

In step 616, the epoxy 306 is cured. In a non-limiting example, the curing time is approximately 48 hours.

In step 618, the polyimide film 302 is separated from the optically flat surface. Compressed air may be injected into the vent provided in step 610 to break the surface tension between the polyimide membrane 302 and the optically planar surface.

In step 620, the surplus polyimide film 302 is trimmed from the substrate. At step 622, the excess epoxy 306 is trimmed from the substrate. Finishing can be accomplished by a variety of techniques that will be understood by those skilled in the art. The polyimide film 302 does not require surface polishing to improve its surface flatness and heat treatment to increase its hardness.

At step 624, the epoxy 306 is further cured by baking the substrate / membrane assembly. In a non-limiting example, the substrate / membrane assembly is baked at 120 degrees Celsius for 12 hours. The baking may be performed in a vacuum chamber.

IV. conclusion

It should be understood that the Detailed Description section of the invention, rather than the Summary and Abstract sections, is intended to be used to interpret the claims. The summary and abstract sections can describe one or more embodiments, but are not intended to limit every embodiment of the present invention contemplated by the inventor (s), and thus should not be construed as limiting the invention and the subsequent claims Do not.

The present invention has been described above with the aid of functional building blocks which illustrate the implementation of specific functions and their associated aspects. The boundaries of the functional building blocks are arbitrarily defined herein for ease of explanation. Alternative boundaries can be defined as long as the specific functions and their relations are properly performed.

The foregoing description of specific embodiments is provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art without departing from the generic concept of the present invention, And the general characteristics of the invention are fully disclosed. Therefore, such adaptations and modifications are intended to be within the meaning and range of equivalents of the disclosed embodiments based on the disclosure and guidance presented herein. It is to be understood that the phraseology and terminology used herein are not for the purpose of description, and are not to be construed as limiting, the jurisdiction or phraseology of the present specification can be construed by one of ordinary skill in the art in light of the present disclosure and guidance.

The breadth and scope of the present invention should not be limited by any of the above-described embodiments, but should be defined only in accordance with the following claims and their equivalents.

Claims (34)

A method of manufacturing a bearing surface of a pneumatic bearing,
Preparing a substrate,
Laminating a bonding layer on the substrate,
Applying a vacuum to the polymeric membrane to form a flat bearing surface, and
And laminating the polymer film on the bonding layer. The method according to claim 1,
Wherein the substrate is made of a material selected from the group consisting of metals, glass, and ceramics. The method according to claim 1,
The bonding layer may be formed of a diglycidyl ether of bisphenol A, 1,4-butanediol diglycidyl ether, and 2,2,4- (2,2,4-trimethylhexamethylen-1,6-diamine). The method according to claim 1,
Wherein the polymer film comprises poly-oxydiphenylene-pyromellitimide. The method according to claim 1,
Wherein the polymer film is at least 25 microns thick. delete A method of manufacturing a bearing surface of an air bearing,
Disposing a polymer film on the flat surface of the vacuum chuck,
Applying a vacuum to the polymeric membrane,
Disposing a liquid epoxy on the surface of the polymer film,
Disposing the substrate on the liquid epoxy so that the polymer film is not in contact with the substrate;
Releasing the substrate onto the liquid epoxy,
Placing a weight on the substrate,
Curing the liquid epoxy,
Removing the weight, and
And releasing the polymer membrane from the vacuum chuck. 8. The method of claim 7,
Further comprising the step of trimming the polymer film to match the contour of the substrate. ≪ RTI ID = 0.0 > 11. < / RTI > 8. The method of claim 7,
Further comprising positioning the vacuum chuck substantially perpendicular to gravity prior to placing the polymer film on a flat surface of the vacuum chuck. 8. The method of claim 7,
Wherein the applying step draws the polymer film to conform to the flat surface of the vacuum chuck. 8. The method of claim 7,
Further comprising pre-mixing and degassing the epoxy prior to placing the liquid epoxy on the surface of the polymeric membrane. 8. The method of claim 7,
Wherein the step of disposing the liquid epoxy comprises placing the shape of the epoxy according to the shape of the substrate. 8. The method of claim 7,
Wherein disposing the substrate comprises maintaining the substrate substantially perpendicular to gravity. ≪ Desc / Clms Page number 17 > 8. The method of claim 7,
Wherein the substrate is released onto the liquid epoxy when the substrate is in the range of 0 to 1 millimeter from the surface of the polymer film. A method of manufacturing a bearing surface of an air bearing,
Coating the substrate with epoxy,
Unrolling the polymer film on the epoxy,
Placing the polymeric film secured to the substrate by the epoxy on an optically flat surface,
Applying a force to the substrate to squeeze excess epoxy, and
Separating the polymeric film from the optically flat surface. ≪ RTI ID = 0.0 > 11. < / RTI > delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete delete

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